The present invention relates generally to fluid treatment systems such as water treatment systems including water softeners, and more particularly to a control valve for a water softening system. It is recognized that many aspects of the present invention can be applied to other types of fluid treatment systems, such as filtering or de-ionizing systems.
“Hard water” refers to hardness ions or metal ions that are present in certain water sources. The metal ions in the water cause three main types of undesired effects. First, the metal ions react with soaps to hinder the soap's ability to form a lather. Second, the metal ions inhibit the cleaning effects of detergents. Third, the calcium and magnesium ions in “hard water” tend to adhere to the surfaces of pipes and heat exchangers. The building up of the ions (i.e., scale) on the surfaces of the pipes, etc. can significantly restrict water flow in the pipes and reduce the heat efficiency of the heat exchangers. Water softeners reduce the dissolved calcium, magnesium, and to some degree, manganese and ferrous iron ion concentration in “hard water” to significantly reduce the undesired effects of hard water.
Conventional water softeners include a raw water source, a treatment tank containing an ion exchange resin, a brine tank containing a brine solution, and a control valve for directing fluids between the source, the tanks and a drain or other output. Water softening occurs by running water through the ion exchange resin, which replaces the calcium and magnesium ions in the water with sodium ions. As the ion exchange process continues, the resin becomes saturated with the metal ions and eventually loses its capacity to soften water. As a result, the resin must be replenished with sodium ions using a process called regeneration. During regeneration, the calcium and magnesium ions are removed and the sodium ions are added back to the resin to restore the resin's capacity to soften water.
During regeneration, brine, a concentrated or saturated salt solution, is passed through the ion exchange resin, where the ions in the resin are replaced with sodium ions. Regeneration is a multi-step process that incorporates a number of cycles, specifically, backwash, brine draw, rinse and refill cycles.
Conventional water softening systems are generally provided with a control valve for controlling the flow of water through the system and the operation of the various regeneration cycles. The control valve directs the water flow between the raw water inlets, the various inlets and outlets of the conditioning tank and the brine tank, the outlet for supplying water to the residence or commercial structure, and the drain. For the valve to operate without leakage, appropriate sealing is necessary.
To provide such sealing, conventional water softening systems typically include a seal pack assembly having a single piston provided within the control valve. However, because the single piston generally reciprocates between several O-ring seals within the seal pack, the O-rings become worn after continued use. Because all of the valve ports are controlled by a single piston, the entire assembly must be removed from the valve when only a single O-ring requires replacement, thereby increasing the cost to the user and reducing the efficiency of the system.
Further, the single seal-pack piston in conventional control valves requires precise positioning to properly control the flow relative to each of the flow passages. If the piston fails to stop in the appropriate position within the valve, the flow path may not be sufficiently open or closed, reducing the flow rates in the desired paths and the operating efficiency of the system.
Also, conventional control valves are generally only configured to run a specific type of regeneration: downflow (i.e., where the brine enters the treatment tank in the same flow direction as the softened water); upflow (i.e., where the brine and softened water enter the treatment tank in opposite flow directions); or in commercial applications, progressive flow (i.e., where several water softeners are linked together). Specifically, the flow paths in conventional control valves are linked together in a fixed relationship because the flow paths all utilize the same single seal-pack piston. Accordingly, the user is unable to alter the water softening system from downflow regeneration to upflow regeneration, without removing and replacing certain internal valve components such as the piston, for example.